The present invention relates to a construction machine with automatic fan rotational speed regulation and to a method for driving a fan.
In construction machines, particularly road pavers and feeders, diesel engines are used as drive motors. Both the diesel engines and the units driven by them have waste heat, conditional on their degree of efficiency, that must be dissipated by means of coolers. In current road pavers, cooling to the required temperatures is brought about via heat exchangers by means of various cooling media, such as cooling water, charge air and/or hydraulic oil, for example. In order to ensure an airflow through the heat exchangers, a fan is an element of the cooling system. It is known to connect the fan rigidly to the diesel engine, so that the fan at all times takes on a fan rotational speed that corresponds to the output rotational speed of the diesel engine.
Also known is the use of a cooling air supply as needed that can be achieved in practice with a hydraulically driven fan in the case of road pavers. This has the disadvantage, however, that hydraulic losses in the fan drive must be accepted. The financial expenditure likewise increases enormously if the degree of efficiency of a hydraulic fan drive is to be optimized. This is because an optimization of the degree of efficiency of the hydraulic fan drive means that it is no longer possible to make use of economical constant flow pumps.